﻿using System;
using System.Collections.Generic;
using System.IO;
using System.IO.Compression;
using System.Linq;
using System.Text;

namespace KLY.Tools.Helper
{
    public static class GZipCompressHelper
    {
        /// <summary>  
        /// 将传入字符串以GZip算法压缩后，返回Base64编码字符  
        /// </summary>  
        /// <param name="rawString">需要压缩的字符串</param>  
        /// <returns>压缩后的Base64编码的字符串</returns>  
        public static string GZipCompressString(string rawString)
        {
            if (string.IsNullOrEmpty(rawString) || rawString.Length == 0)
            {
                return "";
            }
            else
            {
                byte[] rawData = System.Text.Encoding.UTF8.GetBytes(rawString.ToString());
                byte[] zippedData = Compress(rawData);
                return (string)(Convert.ToBase64String(zippedData));
            }

        }

        /// <summary>  
        /// GZip压缩  
        /// </summary>  
        /// <param name="rawData"></param>  
        /// <returns></returns>  
        public static byte[] Compress(byte[] rawData)
        {
            using (MemoryStream ms = new MemoryStream())
            {
                GZipStream compressedzipStream = new GZipStream(ms, CompressionMode.Compress, true);
                compressedzipStream.Write(rawData, 0, rawData.Length);
                compressedzipStream.Close();
                return ms.ToArray();
            }
        }

        /// <summary>  
        /// 将传入的二进制字符串资料以GZip算法解压缩  
        /// </summary>  
        /// <param name="zippedString">经GZip压缩后的二进制字符串</param>  
        /// <returns>原始未压缩字符串</returns>  
        public static string GZipDecompressString(string zippedString)
        {
            if (string.IsNullOrEmpty(zippedString) || zippedString.Length == 0)
            {
                return "";
            }
            else
            {
                byte[] zippedData = Convert.FromBase64String(zippedString.ToString());
                return (string)(System.Text.Encoding.UTF8.GetString(Decompress(zippedData)));
            }
        }

        /// <summary>  
        /// ZIP解压  
        /// </summary>  
        /// <param name="zippedData"></param>  
        /// <returns></returns>  
        public static byte[] Decompress(byte[] zippedData)
        {
            using (MemoryStream outBuffer = new MemoryStream())
            {
                using (MemoryStream ms = new MemoryStream(zippedData))
                {
                    using (var compressedzipStream = new GZipStream(ms, CompressionMode.Decompress))
                    {
                        byte[] block = new byte[1024];
                        while (true)
                        {
                            int bytesRead = compressedzipStream.Read(block, 0, block.Length);
                            if (bytesRead <= 0)
                                break;
                            else
                                outBuffer.Write(block, 0, bytesRead);
                        }
                        compressedzipStream.Close();
                    }
                }
                return outBuffer.ToArray();
            }
        }
    }
}
